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Myiasis Producing Flies (view source)
Revision as of 12:52, 13 January 2009
, 12:52, 13 January 2009no edit summary
*Similar to [[Myiasis Flies - WikiBlood#Calliphoridae|''Calliphora'']] in appearance
*Similar to [[Myiasis Flies - WikiBlood#Calliphoridae|''Calliphora'']] in appearance
**Blue/black
**Blue-black
**Yellow/orange head and legs
**Yellow-orange head and legs
*Larvae are distinctive as they taper towards the posterior end
*Larvae are distinctive as they taper towards the posterior end
'''Life Cycle'''
*Eggs laid on blood sucking flies
'''Life cycle'''
**E.g. On mosquitos, which hatch when the mosquito next lands on a warm blooded animal
*Eggs laid on blood sucking flies such as mosquitoes
**These hatch when the mosquito next lands on a warm blooded animal
*Larvae penetrate skin causing painful swellings
*Larvae penetrate skin causing painful swellings
*Larvae emerge after 35-42 days and fall to ground to pupate
*Larvae emerge after 35-42 days and fall to ground to pupate
*4 month life cycle
*'''4 month''' life cycle
'''Pathogenesis'''
'''Pathogenesis'''
*Wounds caused by exiting larvae can increase the prevalence of attack by other myiasis flies
*Wounds caused by exiting larvae can increase the prevalence of attack by other myiasis flies
==Calliphoridae==
==Calliphoridae==
*The damage the larvae cause to the animal is known as '''strike'''
*The damage the larvae cause to the animal is known as '''strike'''
*Worldwide
*Worldwide distribution
*Affects sheep mostly
*Affects sheep mostly
**Rabbits can also be affected
**Rabbits can also be affected
*''Phormia terra-novae''
'''Species of veterinary importance in the Europe'''
**Blackbottle
*''Lucilia sericata''; Greenbottle
*''Phormia terra-novae''; Blackbottle
*''Calliphora erythrocephala''; Bluebottle
*''Callipohora vomitoria''; Bluebottle
'''Species of veterinary importance in the Tropics'''
**Bluebottle
*''Lucilia cuprina''; South Africa and Australia
*''Lucilia cuprina''
*''Chrysomya spp.''; Africa, Asia and Australia
*''Chrysomya'' spp.
*''Wohlfahrtia''; Fleshfly
'''Recognition of Adults'''
'''Recognition of Adults'''
*Clear wings
*Clear wings
'''Recognition of Larvae'''
'''Recognition of Larvae'''
*Spiracles and stigmatic plates on the tail can be used for species differentiation
*Spiracles and stigmatic plates on the tail can be used for species differentiation
'''Life Cycle'''
'''Life cycle'''
*Eggs laid in wounds, soiled fleece and on carrion
*Eggs laid in wounds, soiled fleece and on carrion
**Females attracted by the odour emitted
**Females attracted by the odour emitted
**Clusters of yellow/cream eggs laid
**Clusters of yellow-cream eggs laid
*Larvae hatch 24 hours later and crawl down onto the skin
*Larvae hatch 24 hours later and crawl down onto the skin
**Process takes 1-2 weeks
**Process takes 1-2 weeks
*Larvae falls to the ground to pupate
*Larvae fall to the ground to pupate
*Adult emerges in under a week (during summer)
*Adult emerges in under 1 week (during summer)
*The female reaches sexual maturity after a protein meal
*The female reaches sexual maturity after a protein meal
**Lays eggs in batches of 100-200
**Lays eggs in batches of 100-200
*Adult flies survive for one month
*Adult flies survive for 1 month
*Between May and September four generations can develop
*'''Between May and September four generations can develop'''
**In warmer climates, up to 9 or 10 generations can develop per year
**In warmer climates, up to 9 or 10 generations can develop per year
*Flies can survive the winter as pupae and emerge the next spring
*Flies can survive the winter as pupae and emerge the next spring
'''Epidemiology'''
'''Epidemiology'''
Blowflies are divided into categories depending on their ability to initiate strike
*Primary flies are capable of initiating a strike on living sheep. Larvae can penetrate intact skin
***E.g. ''Lucilia'', ''Phormia'' and ''Calliphora''
**''Lucilia''
**''Phormia''
***E.g. ''Calliphora'' and ''Chrysoma'' (in warmer climates)
**''Calliphora spp.''
***E.g. ''Musca'' and ''Sarcophaga'' spp.
*Secondary flies cannot initiate a strike. Larvae attack an area already struck or damaged, extending it
**''Calliphora spp.''
**''Chrysomya spp.'' (in warmer climates)
*Tertiary flies attack lesions on carcasses which have become dry
**''Musca''
**''Sarcophaga spp.''
*Temperature will affect the prevalence of strike
Predisposing factors to flystrike
*Temperature
**Temperature in the spring will determine when the overwintering larvae hatch
**Temperature in the spring will determine when the overwintering larvae hatch
**High temperature and humidity will create a microclimate in the fleece, attracting adult flies to lay eggs
**High temperature and humidity will create a microclimate in the fleece, attracting adult flies to lay eggs
*Persistent rainfall will make the fleece microclimate attractive to adult flies
*Rainfall
**Persistent rainfall will make the fleece microclimate attractive to adult flies. Females lay eggs after the rain ceases
**Breeds with long, fine wool are the most susceptible
**Breeds with long, fine wool are the most susceptible
*Host susceptibility is increased when putrefactive odours develop on the fleece due to bacterial decomposition of organic matter
*Host susceptibility
**This is increased when putrefactive odours develop on the fleece due to bacterial decomposition of organic matter following soiling with urine or faeces
**Merino sheep have a narrow breech area with excessive wrinkling making them more susceptible to soiling
**Merino sheep have a narrow breech area with excessive wrinkling making them more susceptible to soiling
**A narrow opening of the penile sheath in rams and wethers may result in accumulation of urine and increase blowfly strike in this area
**A narrow opening of the penile sheath in rams and wethers may result in accumulation of urine and increase blowfly strike in this area
**Cuts during shearing, fighting and barbed wire will also increase the incidence of blowfly strike
**Cuts during shearing, fighting and barbed wire will also increase the incidence of blowfly strike
Blowfly season
*Temperate regions in '''June to September'''
**Mostly in unshorn sheep in June
**Lambs from July to September
*Warmer regions have a more prolonged season due to greater number of blowfly generations
'''Pathogenesis'''
'''Pathogenesis'''
*Risk of strike is highest in warm, moist weather
*Risk of strike is highest in warm, moist weather
'''Clinical Signs'''
*Anorexia, listlessness, animals standing apart from flock
'''Clinical signs'''
*Anorexia
*Listlessness
*Animals standing apart from flock
*Fleece may appear darker, be damp and have a foul smell
*Fleece may appear darker, be damp and have a foul smell
'''Control'''
'''Control'''
*Prophylactic [[Ectoparasiticides|insecticide]] treatment
*Prophylactic [[Ectoparasiticides|insecticide]] treatment
**Must kill larvae and remain in fleece to prevent flies from laying eggs
**Must kill larvae and remain in fleece to prevent flies from laying eggs
**Spraying, dipping, spray race or jetting
**Applied by spraying, dipping, spray race or jetting
*Insect growth regulators
*Insect growth regulators
**To minimise diarrhoea and therefore soiled fleece
**To minimise diarrhoea and therefore soiled fleece
*Crutching
*Crutching to prevent soiling
*'Mule's operation'
*'Mule's operation'
*Vaccination
*Vaccination
**Experimental use against ''Luculia cuprina'' in Australia
===Screw Worm Myiasis===
===Screw Worm Myiasis===